To meet customer demands, image output devices such as a printer or display need to produce a consistent spectrum of colors over time. For example, customers want a printing system to produce a particular colored document consistently from day to day, or print job to print job. To control the color rendering consistency of a printing device, the printing device is typically characterized and calibrated prior to being shipped to a customer. The characterization and calibration process produces a set of LUTs (look-up tables) which correlate a standardized set of target colors with the appropriate device dependent color space values necessary to produce the target colors with the printing device. For example, a Pantone® color spectrum may be utilized as a color target reference and the LUTs produced by the characterization and calibration process are device dependent CMYK color space representations of the Pantone target colors. This characterization and calibration process is generally referred to as profiling a device or printer. To accomplish the profiling of a printing device, a spectrophotometer or other image sensing device is used to measure the colorimetric properties of the produced images. These measured colorimetric properties provide an objective basis of comparison to the reference target color set and provide the necessary feedback to iteratively generate accurate device dependent LUTs. Stated another way, device independent CMYK values are correlated to the reference target color set, and the LUT correlates the reference target color set device independent CMYK values to the device dependent CMYK values. Device profiling can also be applied to a display where an image sensing device is approximately located to the display for colorimetric measurements of the displayed image. In addition, multiple LUTs may be generated for an image output device to account for multiple media types and/or half tone screens.
One primary goal of the color management system is to effectively transform variety of images to device CMYK color separations for printing by the engine. In a cascade strategy, a fleet profile that represents a typical printer and having many profiling strategies incorporated with appropriate GCR converts the images to a set of typical CMYK. The engine takes this set of typical CMYK and converts to its own device cmyk for printing. Advantages of a cascade strategy are that It can have one DFE with the fleet profile to drive a set of engines so that cost will be lower and it has a clean separation between the DFE and the engine so that development of the DFE and the engine color management system can be separated. When the engine changes or drifts the 4×4 needs to be updated to account for the change. A usual way of updating the 4×4 is to print the printer model patches for the engine, construct a printer model, and then re-compute the 4×4. However, since the printer model typically has about 2 deltaE2000 error, a more accurate way to update the 4×4 is by iterating a set of patches that can be projected to the 4×4 on the printer. The above-mentioned problem of inheriting color management intent from a fleet color management LUT into a 4×4 cascaded LUT of an individual engine remains to be addressed.
Accordingly, what is needed in this art are systems and methods for compensating for an amount of print engine change, such as engine drift, which adversely impacts the quality of an output print rendered using a document reproduction device.